Freezing artifacts and rapid use of energy reserves have posed problems in studying energy utilization in the mammalian nervous system. Insects, in turn, because of small size and reduced rates of energy use appear well suited to such studies. Objectives: 1. Correlate the level of neural activity with the energy reserves available in the cockroach nerve cord. a. Determine the energy level at which spontaneous activity and preganglionic stimulated synaptic transmission stop in the anoxic nerve cord. b. Establish whether or not cessation of nerve cord electrical activity can be correlated with ATP depletion. 2. Measure the increase in energy use which occurs with an increase in nerve cord stimulation. 3. Determine if the energy reserve in the cellular components of the ganglia differs from that in the synaptic neuropile when spontaneous and stimulated neuronal activity stop in an anoxic atmosphere.